The research hypothesis for this renewal proposal is that frequent host contacts and multiple blood feeding by Ae. aegypti in a single gonotrophic cycle are important contributions to transmission of dengue (DEN) viruses. Our preliminary data show that the assumption that Ae. aegypti feed only once during each egg laying cycle is incorrect and grossly underestimates the potential for spread of disease by this mosquito. Because multiple feeding can greatly increase the chances for a mosquito to contract or transmit a viral infection, an improved understanding of the frequency of host contact by vectors is fundamental for understanding DEN virus transmission and may contribute to knowledge regarding arthropod-borne diseases in general. We seek to study the role of Ae. aegypti multiple feeding behavior in DEN transmission in increasing detail and, in so doing, to test questions that are refinements of our current research. Our Progress Report for 3 years of study with Ae. aegypti in Puerto Rico and Thailand indicates that (1) multiple feeding on humans is common, and the time interval between meals may fluctuate in concert with changes in DEN transmission; (2) frequent blood feeding contributes to mosquito energy needs because females rarely feed on plant sugars; and (3) there is geographic variation in entomological factors that may influence vectorial capacity and, thus, virus transmission. Experiments described in this proposal are designed to determine (1) the distribution of multiple meals within a community by identifying the exact person(s) from which Aedes aegypti imbibe blood; (2) nutritional correlates and reproductive fitness associated with multiple feeding behavior; and (3) if mosquito survival is correlated with the frequency of multiple feeding and seasonal dynamics of DEN transmission. information gathered from these studies will be important to people involved in disease prevention through vector control and in basic studies of arboviral ecology and evolution.